The fossil was found in ocean layers where the giant shark has also been recorded and the authors suggest that these two giant, raptorial predators could have lived in the same area, feeding on large, marine vertebrates, such as baleen whales.

For decades it sat in a garden on the Chadwick School campus — a 700-pound Altamira shale boulder with a fossil partially exposed.

What that fossil turned out to be surprised most everyone.

Paleontologists from the Los Angeles County Natural History Museum suspect the find could be nothing short of a new, prehistoric sperm whale species from the Palos Verdes Peninsula, which once was underwater.

The fossil is thought to be about 12 million years old, said Howell Thomas, senior paleontologist for the museum.

“I expect it to be something new,” said Thomas, who visited the private school campus about a year ago to inspect the find.

“It’s pretty remarkable and scientifically significant,” said Chadwick science teacher Martin Byhower, who contacted the museum last year with a request for help in identifying that fossil and several other embedded marine fossils used in landscaping on the campus. The other shale rocks contained fossil remnants of ribs and vertebrae from whales but did not qualify as any kind of significant discovery, Thomas said.

“I looked at them and said ‘That’s this, this is that — and this (the skull) needs to come to the museum,’” Thomas said.

“I looked at it and said, ‘Ah! That’s a sperm whale skull and it’s really small,’ which makes it even more important. Juveniles are rare.”

Animals in the wild grow up quickly, he said, making it unlikely that the small size points to a juvenile. More likely, he said, the fossil appears to be from a small adult species of sperm whale that hasn’t previously been identified by scientists.

The museum will collect the piece on Wednesday and take it back to its laboratories for what will be a year’s work of further excavation and study, Thomas said.

Using state-of-the-art tools, the ancient and delicate fossil material will be painstakingly separated from the shale rock that covers perhaps 75 percent of the skull.

As part of the research, the museum will attempt to locate another small sperm whale fossil also reportedly found on the Palos Verdes Peninsula but not on Chadwick property, to compare the two, Thomas said.

The embedded skull appears to have been on the private school campus for nearly 80 years, most likely uncovered during earlier construction projects.

Byhower said it’s been moved a few times during his 30 years of teaching at the school.

Fellow science teacher and Chadwick alumni Nick Herzik said the find is “priceless.”

“I probably sat on this a million times” as a student,” he said.

For Byhower, learning more about the fossils was a way to encourage his students’ natural curiosity about the world around them.

“I just want kids to observe and wonder about the world. I want them to persist until they get the answers” to the mysteries that surround them, Byhower said.

The museum and school have been in negotiations for the past year, Thomas said, to finalize an agreement to have the rock and fossil transported and donated. In exchange, the school will receive a cast model of the fossil when it is finished.

The museum will document its work and likely write a paper for publication when the examinations are complete.

There is “no guarantee” that the find will result in identifying a new species, Thomas said.